Process for reducing the luster of textile materials



March 7, 1961 R. J. MANN ETAL 2,974,065

PROCESS FOR REDUCING THE LUSTER OF TEXTILE MATERIALS Filed Oct. 17, 1957 PREPARING AQUEOUS MELAMINE/FORMALDEHYDE SOLUTION CONTAINING ACID CATALYST AND NON-'IONIC DISPERSING AG NT PRODUCING TEXTILE FABRIC PADDING FABRIC WITH SOLUTION STEAMING SCOURING DRYING United States Pat ent-O PROCESS FOR REDUCING THE LUSTER OF TEXTILE MATERIALS Ralph James Mann and Jozef Biedawski, Spondon, near Derby, England, assignors to British Celanese Limited, a corporation of Great Britain Filed Oct. 17, 1957, Ser. No. 690,615

Claims priority, application Great Britain Nov. 1, 1956 I 10 Claims. (Cl. 117-1193) This invention relates to effecting a reduction of the lustre of textile materials, particularly fabrics, especially those of cellulose acetate or other cellulose esters of lower fatty acids.

It is well known that the lustre of lustrous textile materials can be reduced by forming on the material, or in the presence of the material, particles of amorphous water-insoluble condensation products of formaldehyde with urea or melamine. Such processes are described in British patent specifications 467,480, 469,688 and 568,- 438. In applying such processes to fabrics of cellulose acetate we have found that the procedures specifically recommended suffer from various defects from a commercial point of view. For instance, we have found it very difiicult to obtain consistently a reduction of lustre sufliciently uniform for commercial purposes and to obtain consistently a given reduction of lustre.

We have now found a new method whereby these dif-' ficulties may be avoided and reduction of lustre effected with a'high degree of uniformity and reproducibility. According to our new process, the reduction of lustre of textile materials, especially those of cellulose acetate or other cellulose esters and lower fatty acids, is effected by uniformly impregnating the material with an aqueous solution of a water-soluble condensation product of melamine and formaldehyde (eg a methylol melamine) the solution containing an acid, particularly a strong organic acid, together with a non-ionic dispersing agent, and then while the material is so impregnated heating it in an atmosphere such that the material remains wet. The acid acts as a catalyst to promote the formation of a white amorphous product from the condensate.

The drawing is a flow sheet of one embodiment of the process of this invention.

The acid employed is preferably of low volatility and advantageously a strong aliphatic carboxylic acid of low volatility; we have obtained particularly good results by the use of aliphatic hydroxy carboxylic acids containing at least two carboxylic groups. The acid is preferably one having a dissociation constant of at least l 10 Examples of such acids are citric acid, tartaric acid and lactic acid. All these acids have dissociation constants below 1 10 but stronger acids of low volatility may be used e.g. acids ranging in strength up to that of phosphoric acid and oxalic acid which have dissociation constants of, about 1 10- and 6.5 l-

' respectively. Very good results can be obtained with citric acid. The concentration of the citric or other acid in the aqueous solution may be from 0.54%, for example 1-2%.

In place of the free acids salts thereof with volatile bases e.g. ammonia or methyl amine may be employed. Thus we may use diammonium phosphate or oxalate or ammonium salts of citric or tartaric acid. When the impregnated-material is heated they dissociate with for- .mation of free acid.

As already indicated the aqueous impregnation liquor ..contains a, non-ionic dispersingagentw This. is a very ice Patented Mar. 7, 1961 washed from the material and impart a glitter to the lat- Again, if a cationic dispersing agent is employed ter. the delustre effect is not sufficiently resistant to washing.

The non-ionic dispersing agent may be one obtainable by condensing ethylene oxide with (a) a fatty acid containing a chain of at least 10 carbon atoms starting from and including the carbon atoms of the carboxyl group,

.e.g. lauric acid, palmitic acid, or oleic acid, or with (b) a fatty alcohol containing a chain of at least 10 carbon atoms starting from and including the carbon atom carrying the hydroxyl group, e.g. lauryl alcohol, cetyl alcohol or oleyl alcohol, or with an alkyl phenol in which the alkyl group contains a chain of at least 4 carbon atoms starting from and including the one directly attached to the benzene ring, e.g. p-n-dodecyl-phenol or p-n-butylphenol. The number of molecules of ethylene oxide per molecule of fatty acid, fatty alcohol, or alkyl-phenol must be sufficient to yield a water-soluble product, for example from 15 to 25 molecules. Commercial products of these kinds 'are Pentrosan A2 sold by Glovers (Chemicals) Ltd., and Dispersol VL sold by Imperial Chemical Industries Ltd., a fatty alcohol/ethylene oxide condensate.

The temperature at which the heating is effected may be from 50 to C. Heating while maintaining the material in the wet state can be effected by heating in air saturated with water vapour, or in saturated steam,

that is in a saturated water vapour atmosphere. .The

fected with a heating time in the range of 2-15 minutes.

Conveniently, in the case of a fabric, the latter is passed continuously through a substantially closed chamber into which steam is injected to bring the atmosphere to the required temperature. To provide conveniently for the requisite time of passage coupled with a reasonable linear speed of passage the chamber may be provided with a series of upper rollers and a series of lower rollers over and under which the fabric passes as in certain types of steamer employed for the steaming'of prints on textile materials. When the impregnation liquor contains a salt of the acid with a volatile base it is desirable that provision be made for removing volatile base from the neighbourhood of the fabric, as by permitting steam to escape from the steaming chamber-so carry away volatile base.

It is very important that the material be not allowed a to become dry during the heating treatment. If itbecomesdry there is a tendency for the melamine/formaldehyde condensation product to be converted intora resinous product having little'effect on the lustre of material.

The Water-soluble melamine/formaldehyde condensation product may be one made by reaction of 1 molecular proportion of melamine with from 1-6 molecular proportions, particularly 3-6 molecular proportions, 1 of formaldehyde. The melamine may be warmed with .the required proportion of aqueous formaldehyde of 30-40% strength, until the melamine is dissolved. Such a condensation product may be diluted with water 'to.' .a strength suitable for application to the material. Before application of the condensate solution to the. material the acid is added together with the non-ionic dispersing agent.

the

concentration corresponding with 4 to 8% of melamine,

but lower concentrations may be used according to the effect desired, e.g. concentrations corresponding with down to 0.5% of melamine.

The proportion of melamine/ formaldehyde condensate applied to the material may be such as corresponds to from 4 to 12% of melamine, particularly 4 to 8%, based on the weight of the textile material. Smaller proportions may be used however, depending on the reduction of lustre required, for example proportions down to that corresponding with 0.5 of melamine.

In place of the free acids salts thereof with volatile bases e.g. ammonia or methyl amine may be employed. Thus we may use diammonium phosphate or oxalate or ammonium salts of critric or tartaric acid. When the impregnated material is heated they dissociate with formation of free acid.

The impregnation of the textile material with the aqueous acid solution of the melamine/formaldehyde condensate, may be effected by padding. Thus a fabric may be padded with the solution by means of a padding mangle, the latter being adjusted so as to leave in the material from 50-100% of its weight of the solution based on the weight of the material.

The melamine/formaldehyde condensates maybe replaced, though usually With less satisfaction, by similar water-soluble condensation products of formaldehyde with urea, thiourea, or ethylene-urea our-NH o o onT-NH or another substance including the grouping (where X is nitrogen, oxygen or sulphur) and capable of reacting with formaldehyde to form a water-soluble product containing at least two methylol groups attached to nitrogen.

The new delustn'ng process may be applied to textile fabrics and other materials of acetone-soluble cellulose acetate. In this way there may be obtained, with a high degree of reproducibility, products of reduced lustre which are resistant to repeated washing with a soap solution at 60 C. Moreover the resultant low lustre material does not re-lustre when ironed wet as is the case with acetone-soluble cellulose acetate fabrics which have been delustred by boiling in hot soap solutions. Again the new process may be very satisfactorily employed to effect reduction of lustre of textile materials of cellulose acetate or other cellulose esters of lower fatty acids, the said esters containing not more than 0.29 alcoholic hydroxyl groups per C unit of the cellulose molecule. Thus the process may be applied to textile fabrics or other textile materials of cellulose acetate of acetyl value at least 59%, e.g. 60.5-62.5% calculated as acetic acid. Such materials cannot be delustred by the simple expedient of boiling with hot soap solutions as is the case with materials of acetone-soluble cellulose acetate. The new process may be applied to uncoloured materials or to already coloured materials as may be desired.

As already indicated, the processes are of particular value for textile materials of cellulose acetate. Textile materials of other cellulose esters of lower fatty acids which may be treated include those of cellulose propionate, cellulose acetate propionate and cellulose acetate butyrate.

Textile materials other than those of cellulose esters which may be treated by the process of the invention include those of regenerated cellulose and thoseof wholly synthetic linear polymers, for example of polyamides, e.g. polyhexamethylene adipamide (nylon 66) or poly-caproamide (nylon 6'), or of polyesters, e.g. polyethylene-terephthalate.

Textile materials which have been treated by the new process may subsequently be scoured in an aqueous solution of a detergent in order to remove acid and any loosely adherent condensation product. The detergent may be anionic for example a long chain fatty alcohol sulphate e.g. sodium oleyl sulphate or sodium lauryl sulphate, or an alkylarylsulphonate, e.g. sodium dodecylbenzenesulphonate.

The invention is illustrated by the following example:

A stock solution of melamine/formaldehyde condensate is prepared by Warming 48 parts by weight of melamine with 180 parts by weight of commercial aqueous formaldehyde of 36-40% strength until the mixture is clear.

A padding solution is prepared of the following compositions:

Melamine/formaldehyde stock solution prepared as above ccs Water ccs 120 Citric acid --g 2.5 Non-ionic dispersing agent cc 5 The non-ionic dispersing agent may be Pentrosan A2 (Glovers) or Dispersol VL (I.C.I.) or a product containing about 35% of active ingredient made by condensing one molecular proportion of lauric acid or oleyl or cetyl alcohol with about 20 molecular proportions of ethylene oxide.

A plain satin fabric or crepe satin fabric of acetonesoluble cellulose acetate is padded with the foregoing solution on a padding mangle adjusted to leave the fabric containing about 80% of its weight of the padding liquor. The fabric is then, while still wet, run as a series of loops through a chamber into which steam is injected so as to give a temperature within the chamber of about 80 C. The duration of the passage of the fabric is from 4-9 minutes. After leaving the steaming chamber the fabric may be scoured, for example with an aqueous bath containing an anionic or non-ionic detergent. Thus the material may be scoured for 3 to 5 minutes at a temperature of 60 C. using a 2 to 5 grams per litre aqueous solution of Perlankrol C27, an anionic detergent sold by Lankro Chemical Co. Ltd. or a l to 2 grams per litre aqueous solution of sodium oleyl sulphate.

The resulting fabrics are of uniformly low lustre which is substantially unaltered by six washings in a 2 g./l. soap solution at 60 C., or by dry-cleaning with white spirit, perchloroethylene or trichloroethylene, and do not re-lustre on ironing in the wet state with a hot iron. They have a pleasant, soft but weighty handle.

Either of the fabrics may subsequently be dyed with disperse dyes in level shades, for example in shades of pale to medium depth. The process described in the foregoing example may be applied with similar results to fabrics of continuous filament yarns of cellulose acetate of acetyl value 61%, calculated as acetieacirl, such as may be obtained by dry-spinning a solution of the cellulose acetate in a mixture of methylene chloride and methyl alcohol in the proportion of 93 to 7 by weight. Again it may be applied to a fabric of yarns of (nylon 66) or (nylon 6).

Having described our invention, what we desire to secure by Letters Patent is:

1. In a process for effecting a reduction of the lustre of textile materials which comprises uniformly impreg mating the material with an aqueous solution containing a catalyst selected from the group consisting of acids and salts thereof with ammonia, said acids being sub stautially non-volatile in steam at C. and of dissociation constant at least 1 10- and a water-soluble condensation product of formaldehyde with a compound selected from the group consisting of melamine, urea, ethylene urea, and thiourea and then heating the impregnated material to a temperature of at least 50 C. under such conditions that the material remains wet, the step of including a non-ionic dispersing agent in the aqueous solution.

2. A process according to claim 1, wherein the heating is effected by the action of an atmosphere, saturated with water vapour, at a temperature of 50 to 100 C.

3. A process according to claim 2, wherein the catalyst is an acid and is an aliphatic carboxylic acid which is substantially non-volatile in steam at 100 C.

4. In a process for effecting a reduction of the lustre of textile materials of cellulose acetate which comprises uniformly impregnatingthe material with an aqueous solution containing an aliphatic carboxylic acid, of dissociation constant at least 1X10 which is substantially non-volatile in steam at 100 C. and a water-soluble condensation product of formaldehyde with melamine, and then heating the impregnated material to a temperature of at least 50 C. under such conditions that the material remains wet, the step of including a non-ionic dispersing agent in the aqueous solution.

5. A process according to claim 4, wherein the heating is effected by the action of an atmosphere, saturated with water vapour, at a temperature of 50 to 100 C.

6. A" process according to claim '5, wherein the impregnated material carries an amount of a melamine/ formaldehyde condensation product equivalent to from 4 to 8% of melamine based on the weight of the material and the acid is present to the extent of 1 to 2 percent based on the weight of the impregnation solution.

7. A process according to claim 5, wherein the acid is citric acid.

8. A process according to claim 5, wherein the acid is tartaric acid.

9. A process according to claim 5, wherein the textile material is a fabric of acetone-soluble cellulose acetate.

10. A process according to claim 5, wherein the textile material is a fabric of cellulose acetate of acetyl value from 60 to 62.5% calculated as acetic acid.

References Cited in the ,file of this patent UNITED STATES PATENTS 2,190,672 .Me'harg Feb. 20, 1940 2,709,141 Burks May 24, 1955 2,804,441 Nickerson Aug. 27, 1957 2,844,488 Meharg et a1. July 22, 1958 2,852,479 Bender Sept. 16, 1958 FOREIGN PATENTS 1 499,207 Great Britain June 16, 1939 

1. IN A PROCESS FOR EFFECTING A REDUCTION OF THE LUSTRE OF TEXTILE MATERIALS WHICH COMPRISES UNIFORMLY IMPREGNATING THE MATERIAL WITH AN AQUEOUS SOLUTION CONTAINING A CATALYST SELECTED FROM THE GROUP CONSISTING OF ACIDS AND SALTS THEREOF WITH AMMONIA, SAID ACIDS BEING SUBSTANTIALLY NON-VOLATILE IN STEAM AT 100*C. AND OF DISSOCIATION CONSTANT AT LEAST 1X10-4, AND A WATER-SOLUBLE CONDENSATION PRODUCT OF FORMALDEHYDE WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF MELAMINE, UREA, ETHYLENE UREA, AND THIOUREA AND THEN HEATING THE IMPREGNATED MATERIAL TO A TEMPERATURE OF AT LEAST 50*C. UNDER SUCH CONDITIONS THAT THE MATERIAL REMAINS WET, THE STEP OF INCLUDING A NON-IONIC DISPERSING AGENT IN THE AQUEOUS SOLUTION. 